The screenplay was written in 2001, but after failed attempts to get the script produced in Wan and Whannell's home country of Australia, they were urged to travel to Los Angeles. In order to help attract producers they shot a low-budgetshort film of the same name from a scene out of the script. This proved successful in 2003 as producers from Evolution Entertainment were immediately attached and also formed a horror genre production label Twisted Pictures. The film was given a small budget of $1.2 million and shot for 18 days.

Saw was first screened on January 19, 2004, before released in North America on October 29, 2004 by Lions Gate Films. Compared to its low budget, Saw performed very well at the box office, grossing more than $100 million worldwide and becoming, at the time, one of the most profitable horror films since Scream (1996). The film was theatrically re-released by Lionsgate, to select theatres, on October 31, 2014 to celebrate its tenth anniversary.[4] A sequel, entitled Saw II, was released in 2005.

Photographer Adam awakens in a bathtub, his ankle chained to a pipe, with oncologist Lawrence Gordon chained across the dilapidated bathroom, with a corpse between them holding a revolver and a microcassette recorder. Both men find a tape in their pockets, and Adam retrieves the recorder. Adam's tape urges him to escape, while Lawrence's tape tells him to kill Adam by six o'clock or his wife and daughter will be killed and he will be left to die. Adam finds a bag containing two hacksaws inside the toilet, which they try to use to cut through their chains, but Adam's saw breaks. Lawrence realizes the saws are meant to be used on their feet, and identifies their captor as the Jigsaw Killer, whom Lawrence knows of because he was once a suspect.

Flashbacks reveal that Lawrence, while discussing the terminal brain cancer of a patient named John Kramer, was approached by Detectives David Tapp and Steven Sing, who found his penlight at the scene of one of Jigsaw’s "games". Lawrence's alibi cleared him, but he agreed to view the testimony of heroin addict Amanda Young, the only known survivor of one of Jigsaw’s traps who believes the killer helped her.

In the present, Lawrence's wife Alison and daughter Diana are held captive at home as their captor watches Adam and Lawrence through a hidden camera. The house is simultaneously watched by Tapp, having been discharged from the police and becoming obsessed with the Jigsaw case, eventually finding Jigsaw's warehouse using the videotape from Amanda's game. There, he and Sing apprehended Jigsaw and saved a man from a drill trap, but Jigsaw escaped after slashing Tapp's throat, and Sing was killed by a shotgun trap. Convinced that Lawrence is Jigsaw, Tapp has continued to stalk him.

In the bathroom, Lawrence finds a box containing two cigarettes, a lighter, and a one-way cellphone, and recalls his abduction in a parking garage by a pig-masked figure. He and Adam stage Adam’s death with a cigarette dipped in the corpse's poisoned blood, but the plan fails when Adam is electrically shocked through his ankle chain. Adam recalls his own abduction: in his photo development room when the power went out, he found a puppet and was attacked by the same pig-masked figure. Alison calls Lawrence at gunpoint and tells him not to trust Adam, who admits that he was paid to take photos of Lawrence, many of which were in the bag containing the hacksaws. Adam reveals his knowledge of Lawrence's affair with one of his medical students, whom he had visited the night he was abducted; revealing why Lawrence is being “tested”. After Adam describes the man who hired him, Lawrence realizes it was Tapp. Adam finds a photo he did not take, of a man staring out a window of Lawrence's house, whom Lawrence identifies as Zep, an orderly at his hospital. As the clock strikes six, Zep moves to kill Alison and Diana.

Alison frees herself and fights Zep for his gun, after he calls Lawrence. The struggle attracts Tapp's attention, and he saves Alison and Diana and chases Zep to the sewers, where he is shot in the chest after a brief struggle. Lawrence, only aware of gunshots and screaming, is shocked and loses reach of the cellphone. In desperation, he saws off his foot and shoots Adam with the corpse's revolver. Zep enters the bathroom to kill Lawrence according to "the rules", but Adam, having survived, bludgeons Zep to death with the toilet tank lid. As Lawrence crawls out of the room, Adam searches Zep's body for a key and finds another recorder, which reveals that Zep was another victim following rules to obtain an antidote for a slow-acting poison he was given. As the tape ends, the corpse rises and is revealed to be John Kramer, the real Jigsaw Killer. He reveals that the key to Adam's chain went down the bathtub drain when Adam first woke up. Horrified, Adam attempts to shoot John with Zep's gun, but John shocks him with a remote. John shuts off the lights, and yells "Game Over" before sealing the door and leaving a helplessly screaming Adam to die.

After finishing film school, Australian director James Wan and Australian writer Leigh Whannell wanted to write and fund a film.[6] The inspiration that they needed came after watching the low-budget independent film The Blair Witch Project. Another film that inspired them to finance the film themselves was Darren Aronofsky's Pi.[7] The two thought the cheapest script to shoot would involve two actors in one room.[8] Whannell said, "So I actually think the restrictions we had on our bank accounts at the time, the fact that we wanted to keep the film contained, helped us come up with the ideas in the film."[9] One idea was to have the entire film set with two actors stuck in an elevator and being shot in the point of view of security cameras.[8]

Wan pitched the idea to Whannell of two men chained to opposite sides of a bathroom with a dead body in the middle of the floor and they are trying to figure out why and how they are there. By the end of the film they realize the person lying on the floor is not dead and he is the reason they are locked in the room. Whannell initially did not give Wan the reaction he was looking for. He said, "I'll never forget that day. I remember hanging up the phone and started just going over it in my head, and without any sort of long period of pondering, I opened my diary that I had at the time and wrote the word 'Saw'."[8] Before instantaneously writing the word "Saw" in a blood-red, dripping font, the two had not come up with a title. "It was one of those moments that made me aware that some things just really are meant to be. Some things are just waiting there to be discovered," Whannell said.[8]

The character of Jigsaw did not come until months later, when Whannell was working at a job he was unhappy with and began having migraines. Convinced it was a brain tumor,[10] he went to a neurologist to have an MRI and while sitting nervously in the waiting room he thought, "What if you were given the news that you had a tumor and you were going to die soon? How would you react to that?"[6] He imagined the character Jigsaw having been given one or two years to live and combined that with the idea of Jigsaw putting others in a literal version of the situation, but only giving them a few minutes to choose their fate.[6]

Wan did not intend to make a "torture porn" film as the script only had one short segment of (alleged) torture. He said the film "played out like a mystery thriller." It was not until the sequels that the plot focused more on torture scenes.[6]

Whannell and Wan initially had $30,000 to spend on the film, but as the script developed it was clear that more funds would be needed.[7] The script was optioned by a producer in Sydney for a year but the deal eventually fell through.[8] After other failed attempts to get the script produced in Australia from 2001 to 2002,[6] literary agent Ken Greenblat read the script and suggested they travel to Los Angeles, where their chances of finding an interested studio were greater.[11] Wan and Whannell initially refused, due to lack of traveling funds but the pair's agent, Stacey Testro, convinced them to go.[11] In order to help studios take interest in the script, Whannell provided A$5,000 (US$5,000) to make a seven-minute short film based on the script's jaw trap scene, which they thought would prove most effective. Whannell played David, the man wearing the Reverse Bear Trap. Working at the Australian Broadcasting Corporation, Whannell and Wan knew cameramen who were willing to provide technical assistance for the short.[12]

I guess the term 'torture-porn' doesn't affect me one way or the other. I don't love the term, nor do I really hate it. For me, it's kind of hard to have any bad feelings about the term, because I guess torture-porn has given me a lot of good things, like being able to work in the film industry and work as a screenwriter. I guess I'm just thankful to be part of a film that made it, and anything after that is just a champagne problem.

—Leigh Whannell (screenwriter) on his feelings of the film being labeled "torture porn."[6]

Wan shot the short with a 16mm camera[10] in over two days and transferred the footage to DVDs to ship along with the script. Whannell wanted to play the lead character in the feature film. The short helped show that Wan and Whannell were a "director-actor team" rather than just wanting to sell the script. Wan said, "Leigh and I just loved the project so much and we wanted a career in filmmaking so we stuck to our guns and said, 'Look, guys, if you want this project, we're coming on board - Leigh has to act in it and I have to direct it."[11]

In early 2003,[13] while in Los Angeles and before they met with producer Gregg Hoffman, Hoffman's friend pulled him into his office and showed him the short. Hoffman said, "About two or three minutes into it, my jaw hit the floor."[14] He quickly showed the short and script to his partners Mark Burg and Oren Koules of Evolution Entertainment.[6] They later formed Twisted Pictures as a horror genre production label.[15] The producers read the screenplay that night and two days later offered Wan and Whannell creative control and 25% of the net profits.[16] Even though Wan and Whannell received "better offers" from studios like DreamWorks and Gold Circle Films, they were not willing to chance Wan's directing and Whannell acting in the lead role.[6] In order to finance the film, Hoffman, Burg, and Koules put up a second mortgage on their Highland Avenue headquarters.[17]Saw was given a production budget of between $1 million and $1.2 million.[note 1]

Cary Elwes was sent the short film on DVD and immediately became interested in the film. He read the script in one sitting and was drawn in by the "uniqueness and originality" of the story.[20] To prepare for his role as an oncologist, he met with a doctor at UCLA's Department of Neurosurgery.[21]

Shawnee Smith, who is not a horror fan,[22] initially refused the role, describing the script as "horrific". However, after watching the short, she agreed to the role, which was the part that Whannell portrayed in the short.[23]

On taking the role of Jigsaw, Tobin Bell said, "I did Saw because I thought it was a fascinating location for a film to be made. These guys locked in a room, to me, was fresh. I did not anticipate the ending when I read the script, so I was quite caught by surprise and it was clear to me that if the filmmakers shot the scene well, the audience would be caught by surprise as well. The film was worth doing for that moment alone."[8]

With a shooting budget of $700,000,[6][24]Saw began principal photography on September 22, 2003[17] at Lacy Street Production Facility in Los Angeles[14] for 18 days.[24] The bathroom was the only set that had to be built.[25]Danny Glover completed his scenes in two days.[26] Due to the tight shooting schedule, Wan could not afford to shoot more than a couple of takes per actor.[27] "It was a really tough struggle for me. Every day, it was me fighting to get the shots I did not get. I had high aspirations, but there's only so much you can do. I wanted to make it in a very Hitchcockian style of filmmaking, but that style of filmmaking takes time to set up and so on," Wan said about the very short shooting schedule.[6] He said the style instead ended up being "more gritty and rough around the edges due to the lack of time and money that we had to shoot the movie with" and it ultimately became the aesthetic of the film.[6]

In post-production, Wan found he did not have enough shots or takes to work with as he was basically shooting rehearsals. Having a lot of missing gaps in the final product, he and editor Kevin Greutert created shots to mend together during editing; such as making a shot look like a surveillance camera feed and using still photographs. "We did a lot of things to fill in gaps throughout the film. Whatever we cut to newspaper clippings and stuff like that, or we cut to surveillance cameras, or we cut to still photography within the film, which now people say, 'Wow, that's such a cool experimental style of filmmaking', we really did that out of necessity to fill in gaps we did not get during the filming," he explained.[6]

The soundtrack was released on October 5, 2004 by Koch Records. Johnny Loftus of AllMusic gave it three out of five stars. He said that Clouser "really nails it with his creaky, clammy score" and that he "understands that Saw's horror only works with a heady amount of camp, and he draws from industrial music in the same way." He particularly liked, "Cigarette"; "Hello, Adam"; and "F**k This S*!t," commenting that they "blend chilling sounds with harsh percussion and deep-wound keyboard stabs."[31]

Lionsgate picked up Saw's worldwide distribution rights at the Sundance Film Festival days before the film premiered on January 19, 2004.[32] There it played to a packed theater for three nights to a very positive reaction.[13] It was the closing film at the Toronto International Film Festival on September 18, 2004.[18] Lionsgate initially planned to release the film direct-to-video, but due to the positive reaction at Sundance, they chose to release it theatrically by Halloween.[16] It was released on October 1, 2004 in the United Kingdom, October 29, 2004 in the United States and December 2, 2004 in Australia. The film was originally rated NC-17 (No children under 17 permitted) by the Motion Picture Association of America for strong graphic violence, though after being re-edited, it was released with an R rating.[25][33] Lionsgate held the first annual "Give Til It Hurts" blood drive for the Red Cross and collected 4,249 pints of blood.[34][35]

On October 31, 2014, in honor of the film's 10th anniversary, Saw was re-released to select theatres for one week.

The release earned only $650,051 in its opening weekend, and is the third lowest-grossing wide opening.[36] At the end of its run, the release had grossed $815,324, bringing the film's overall domestic gross to $56,000,369.[37]

The theatrical version of the film was released on VHS and DVD on February 15, 2005 in the United States. After its first week, it made $9.4 million in DVD rentals and $1.7 million in VHS rentals, making it the top rental of the week.[38] For the second week it remained as the number one DVD rental with $6.8 million, for a $16.27 million two-week total. It dropped to third place in VHS rentals with $1.09 million, for a $2.83 million two-week total.[39] The film went on to sell more than $70 million worth of video and DVDs.[13] A two-disc "Uncut Edition" was released on October 18, 2005 to tie in with the release of Saw II. The short film, also entitled Saw, was included on the DVD.[40] The film was subsequently included in a boxed set with all six sequels entitled Saw: The Complete Movie Collection, which was released in September 2014 for the film's tenth anniversary. The set contained the unrated editions of all seven films, though it lacked any of the special features from previous releases.[41]

Full Disclosure Report is a 2005 mockumentary, pseudo-documentary set in the Saw franchise, taking place between the events of Saw and Saw II, around one year after the beginning of the Jigsaw murders, following television host Rich Skidmore as he commentates on the murders and the police work in the yet-unresolved case. Donnie Wahlberg appears as Detective Eric Matthews, prior to his appearance in Saw II.

Saw opened at #3 on Halloween weekend 2004 in 2,315 theaters and grossed $18.2 million, behind Ray ($20 million) and The Grudge ($21.8 million).[42] According to Lionsgate's exit poll, 60% of the mostly male audience was under 25 years of age. Saw had also become Lionsgate's second best opening, after Fahrenheit 9/11's$23.9 million (2004).[43] On its second weekend, an additional 152 theaters were added, bringing the theater count to 2,467. It dropped to number four, making $11 million, a 39% drop from the opening weekend.[44]

Saw opened in the United Kingdom to $2.2 million in 301 theaters, grossing a $12.3 million total in seven weeks.[45] In Australia, it opened in 161 theaters with $1.2 million and totaled out to $3.1 million in six weeks.[46] In Italy, the film opened on January 14, 2005 in 267 theaters to $1.7 million and grossed $6.4 million in six weeks.[47]Saw opened to $1.5 million 187 theaters in France on March 16, 2005 and made $3.1 million by the end of its four-week run.[48]Saw came to gross $55.1 million in the United States and Canada and $47.9 million in other markets for a worldwide total of $103 million.[1] It is the second lowest-grossing film in the series after Saw VI.[49] At the time, it became the most profitable horror film after Scream (1996).[50]

Critical reception to Saw was mixed. On review aggregator Rotten Tomatoes, the film has a rating of 49% based on 184 reviews, with an average rating of 5.53/10. The site's consensus reads, "Saw ensnares audiences with a deceptively clever plot and a myriad of memorable, nasty set pieces, but its lofty ambitions are undercut by a nihilistic streak that feels more mean than profound."[51] Metacritic gave the film a score of 46 out of 100, based on 32 critics, indicating "mixed or average reviews".[52]

Dennis Harvey of Variety gave the film a negative review after its Sundance premiere. He called it a "crude concoction sewn together from the severed parts of prior horror/serial killer pics." He called the screenplay "convoluted," criticizing the use of "flashbacks within flashbacks" and red herrings. He described the film as being "too hyperbolic to be genuinely disturbing."[2] Carla Meyer of the San Francisco Chronicle gave the film a positive review saying the film "combined B-movie acting with a twisted mind-set and visual tricks designed to camouflage cheap effects" and that it was "terrifying at some moments and insinuatingly creepy at many others." She called the killing scenes "amazingly evocative for such a low-budget movie."[53]

Empire'sKim Newman gave the film four out of five stars. He said Saw is styled like early David Fincher films and "boasts an intricate structure - complex flashbacks-within-flashbacks explain how the characters have come to this crisis - and a satisfying mystery to go with its ghastly claustrophobia." He ended his review saying, "As good an all-out, non-camp horror movie as we've had lately."[54]Owen Gleiberman of Entertainment Weekly gave the film a B minus, calling it "derivative and messy and too nonsensical for its own good." He described Jigsaw's intent as "to show you the serial killer lurking inside yourself." Gleiberman criticized Elwes' performance by saying, "[Elwes] ought to be featured in a seminar on the perils of overacting."[55]Daniel M. Kimmel of the Telegram & Gazette called it "one of the most loathsome films this critic has seen in more than 20 years on the job."[56]

The New York Times'sStephen Holden gave a mixed review saying the film "does a better-than-average job of conveying the panic and helplessness of men terrorized by a sadist in a degrading environment, but it is still not especially scary. What sets its demon apart from run-of-the-mill movie serial killers is his impulse to humiliate and torture his victims and justify it with some twisted morality." He said the film is "seriously undermined by the half-baked, formulaic detective story in which the horror is framed."[57] Carina Chocano of the Los Angeles Times also gave the film a mixed review saying, "Saw is so full of twists it ends up getting snarled. For all of his flashy engineering and inventive torture scenarios, the Jigsaw Killer comes across as an amateur. Hannibal Lecter would have him for lunch." She said the film "carelessly underscores its own shaky narrative at every turn with its mid-budget hokiness." She also noted that Elwes and Whannell had trouble keeping an American accent.[58] Another mixed review came from Roger Ebert, who gave the film 2 out of 4 stars and lamented the gimmicks and plot contrivances but nonetheless described Saw as "well made and acted, and does what it does about as well as it could be expected to."[59]

When asked if the 1995 thriller film Seven was an inspiration to Saw, Whannell said "For me as the writer, definitely. I mean, Seven is just a very well constructed film, and if you're writing a thriller, it can't hurt to study it. In terms of the story though, James and I never really felt Seven was that close to our film. I guess if you stand back, you have two detectives chasing a psychopath, who uses vile methods to teach people lessons, and those points echo Seven. What we always liked about Saw, though, was the fact that the story is told from the point of view of two of the psychopath's victims, instead of the police chasing after him, as you so often see."[10]Entertainment Weekly's Owen Gleiberman compared the plot to Seven saying, "In a blatant imitation of Seven, Saw features a lunatic sadist whose ghoulish crimes are meant, in each case, to mirror the sins of his victims. The twist here is that the psycho doesn't do the killing."[55] Richard J. Leskosky of Champaign-Urbana's The News-Gazette said "Saw wants to be taken as another Seven. Though it features perverse gross-out scenes and a villain with a superficially pedantic motive behind his crimes (his victims, if they survive, have learned to appreciate life more), it lacks the finesse and polish of the David Fincher film."[60]

Bloody Disgusting ranked the film tenth in its list of the Top 20 Horror Films of the Decade, with the article calling Saw "perhaps the most influential horror film of the decade, which kick-started a franchise. ... In light of its measly $1.2 million price tag the film's quality relative to bigger-budget horror films is striking. It also takes itself seriously, which came as a breath of fresh air following the trend of wimpy tongue-in-cheek horror that had dominated the multiplexes post-Scream. More than anything, this twisted morality tale is a film made by horror fans, for horror fans; it's gory, it's depraved, and best of all it introduced a new horror icon in Jigsaw."[61]The Daily Telegraph listed the film number 14 on their Top 100 list that defined the 2000s.[62]